A hospital bed must generally have the ability to raise and descend. The lower position allows for the facile and safe entering upon and departing from off the bed. The higher position provides a convenient surface for the examination and treatment of the patient.
Moreover, positions tilted from the horizontal produce medical benefits for a number of maladies. Accordingly, beds for hospitals or other treatment facilities often include mechanisms which permit at least one end of the bed to raise higher than the other. Preferably either end may assume a higher position.
F. Pruim et al's U.S. Pat. No. 3,222,693 shows a bed with elevation and tilting mechanisms. That bed, however, descends to its lowest position before inclining into a Trendelenburg position. As a result, when in a tilt, the bed hovers near the floor. However, a patient in a Trendelenburg position often needs the intensive care of others. The lowness of this bed makes that care more difficult.
Another bed which also assumes a Trendelenburg position from its lowest elevation appears in U.S. Pat. No. 3,478,372 issued to R. A. Benoit et al. As with Pruim et al., this bed has two torque tubes which rotate in the same direction in elevating the bed, which they also do in lowering the bed. To overcome the translation thus introduced, Benoit et al. have double linked arms on the torque tubes, as well as telescoping legs.
U.S. Pat. Nos. 2,527,111 to A. Widrich and 3,149,348 to W. A. Hillenbrand show beds without Trendelenburg mechanisms. While possessing torque tubes which rotate in opposite directions to raise or lower the bed, the tubes do not appear on the bed frame undergoing elevation or lowering. Consequently, each possess auxiliary guiding means to retain the mattress in the proper position.
T. Nelson, in his U.S. Pat. No. 3,220,020 shows the opposite rotation of components to elevate a bed. However, his bed also requires telescoping legs which limit the total possible elevation as well as deleteriously extending the external dimensions of the bed.
Recent significant improvements in adjustable beds appear in the U.S. Pat. Nos. 3,711,876 to Kirkland et al. and 3,821,821 to F. J. Burst et al. However, the search continues for elevating and Trendelenburg mechanisms providing greater versatility, longevity and compactness.